It is well known from the art, that the most important pathogenic fungi of cereals (e.g. wheat, barley) are as follows:
smut diseases, such as bunt smut of wheat (Tilletia foetida), loose smut of barley (Ustilago nuda) and the fusarium species (Fusarium spp.) which infect the plant at the embryo stage partly in the soil, partly internally in the seed; PA0 powdery mildew species (e.g. Erypsiphe graminis) which attack the plant at various stages during its life; PA0 cereal fusarium fungi (Fusarium graminearum) and rusts (e.g. Puccinia glumarum) which attack the corn after earing.
The infections of the plant germs are treated by seed-dressing, while the later fungal attacks are treated with foliar spray application of different kinds of fungicides.
So far mercury containing compounds have been used for seed-dressing of corn. However, these compounds have several disadvantages. The health-detrimental and accumulating effect of mercury containing compounds is well known and the compounds do not protect the seeds from internal infections either.
Thus new fungicidal agents have become necessary, which are at least so effective as the mercury containing substances but are not that toxic.
U.S. Pat. Nos. 3,249,499, 3,393,202 and 3,454,391 and FR Pat. Nos. 1 477 059 and 1 477 060 disclose 2,3-dihydro-5-carboxamido-6-methyl-1,4-oxathiines as fungicidal agents.
In FR Pat. Nos. 1 477 061 and 1 477 062 and U.S. Pat. Nos. 3,402,241 and 3,454,391 derivatives are described in which in the ring one or two oxygens are attached to the sulphur atom, i.e. sulfoxides and sulfones. The utility of oxathiines for protection of plants and seeds against plant pathogenic fungi is mentioned. A disadvantage, however is their inefficiency against several species, such as Penicillium sp., Septaria nodorum etc.
In Hungarian patent specification No. 171,736 the very favorable fungicidal effect of the mixed liganded (8-oxyquinolate)-(dimethyl dithiocarbamate) metal complexes are described. Said metal complexes are always more effective--especially if the central atom is zinc, manganese, copper, magnesium, iron, cadmium etc.--than the metal complexes of either 8-oxyquinolate or dimethyl dithiocarbamate comprising the same ligand. It is further reported, that a mixture containing 1 part by weight of zinc complex and 1 part by weight of manganese complex is preferred.
According to HU-PS 158 608 the fungicidal spectrum off 2,3-dihydro-5-carboxanilid-6-methyl-1,4-oxathiines can be considerably broadened and in many cases an unexpected synergistic activity can be achieved by combining a salt or ester of 8-hydroxyquinoline, such as copper salt thereof, e.g. copper-8-quinolinolate, or its sulphate or benzoate and said oxathiines. Particularly good result was achieved by combining copper-8-quinolinate and carboxanilide-oxathiine at a ratio of 1:15-3:5 against fungi belonging to Basidiomycetes, such as Rhizoctonia Kuhl and Uromyces phasecoli typica Arth (plant pathogen, fungi in soil). These fungicidal agents were especially effective against inner fungi in the seeds of cereals, transferred by seeds, such as Ustilago nuda, against which only hot-water treatment proved to be efficient earlier. No biological activity test result was included in the specification and activity of this composition was confirmed only against Septoria nodorum, Fusarium nivale and Penicillium sp.